The present invention relates generally to optoelectronic assemblies having optical components and methods for making the same; and, more particularly, to a method for aligning optoelectronic components including a diode, an optical fiber, and a flexure mounted on a planar or quasi-planar substrate.
Optoelectronics packaging is one of the most difficult and costly operations in optoelectronics manufacturing. Optoelectronic packages provide submicron alignment between optical elements, high-speed electrical connections, excellent heat dissipation, and high reliability. Providing such features has resulted in optoelectronic packages that are larger, costlier and more difficult to manufacture than electronic packages. In addition, current designs of optoelectronic packages and associated fabrication processes are ill adapted for automation because today""s high-performance butterfly packages are characterized by a large multiplicity of mechanical parts (submounts, brackets, ferrules, etc.), three-dimensional (3D) alignment requirements, and poor mechanical accessibility.
One type of package for an edge-coupled optoelectronic device includes a cover with a window, so that an optoelectronic device, such as a laser, may be coupled to external optics, such as a lens or an optical fiber. See, for example, U.S. Pat. No. 4,953,006 by Kovatz. Although this type of package can provide hermeticity and high-speed electrical connections, it does not provide for a way to mount and align collimation or coupling optics nor optical fibers.
U.S. Pat. No. 5,005,178 by Kluitmans and Tjassens and U.S. Pat. No. 5,227,646 by Shigeno also disclose packages for optical and optoelectronic components. Kluitmans et al. discuss a package for a laser diode coupled to an optical fiber. The package includes a conducting rod so that the laser may be used at high speed. Shigeno describes a heat sink for cooling an enclosed laser diode, where the laser diode is preferably coupled to an optical fiber. However, in both of the above patents, it is difficult to align the laser diode with the optical fiber when constructing the package. Both designs use numerous parts in complex three dimensional arrangements and are unsuitable for automated assembly. U.S. Pat. No. 5,628,196 by Farmer discloses a package including a heat sink for a semiconductor laser, but provides no efficient means for coupling the laser to other optics.
In most current types of packages, it is difficult to align the laser diode with the optical fiber when constructing the package. The process of aligning an optical fiber to a laser diode and fixing it in place is known as fiber pigtailing. Current designs use numerous parts in complex three-dimensional arrangements and are unsuitable for automated assembly.
The difficulty in alignment during fiber pigtailing is made more problematic where welding is involved in the manufacturing of a package. The result of the welding process causes a shift to occur in the structure being welded due to shrinkage of the molten weld material while it is solidifying. Therefore, even though a component may be aligned prior to welding, the result of the welding process may cause such shifts to occur. Where micron accuracy is needed, these shifts affect the overall yield. Current techniques to reduce the effect of such post weld shifting include pre-compensation for post weld shifting, laser hammering, or xe2x80x9cbendingxe2x80x9d of the parts after welding.